Package Summary  Overview Summary

class:PhantomReference [CHANGED]



  • public class PhantomReference<T>
    extends Reference<T>
    Phantom reference objects, which are enqueued after the collector determines that their referents may otherwise be reclaimed. Phantom references are most often used for scheduling preto schedule post-mortem cleanup actions in a more flexible way than is possible with the Java finalization mechanism. If.

    Suppose the garbage collector determines at a certain point in time that the referent of a phantom referencean object is phantom reachable , then at. At that time it will atomically clear all phantom references to that object and all phantom references to any other phantom-reachable objects from which that object is reachable. At the same time or at some later time it will enqueue thethose newly-cleared phantom references that are registered with reference queues.

    In order to ensure that a reclaimable object remains so, the referent of a phantom reference may not be retrieved: The get method of a phantom reference always returns null. Unlike soft and weak references, phantom references are not automatically cleared by the garbage collector as they are enqueued. An object that is reachable via phantom references will remain so until all such references are cleared or themselves become unreachable.

    Since:
    1.2


  • public class PhantomReference<T>
    extends Reference<T>
    Phantom reference objects, which are enqueued after the collector determines that their referents may otherwise be reclaimed. Phantom references are most often used for scheduling pre-mortem cleanup actions in a more flexible way than is possible with the Java finalization mechanism.

    If the garbage collector determines at a certain point in time that the referent of a phantom reference is phantom reachable , then at that time or at some later time it will enqueue the reference.

    In order to ensure that a reclaimable object remains so, the referent of a phantom reference may not be retrieved: The get method of a phantom reference always returns null.

    Unlike soft and weak references, phantom references are not automatically cleared by the garbage collector as they are enqueued. An object that is reachable via phantom references will remain so until all such references are cleared or themselves become unreachable.

    Since:
    1.2


  • public class PhantomReference<T>
    extends Reference<T>
    Phantom reference objects, which are enqueued after the collector determines that their referents may otherwise be reclaimed. Phantom references are most often used to schedule post-mortem cleanup actions.

    Suppose the garbage collector determines at a certain point in time that an object is phantom reachable . At that time it will atomically clear all phantom references to that object and all phantom references to any other phantom-reachable objects from which that object is reachable. At the same time or at some later time it will enqueue those newly-cleared phantom references that are registered with reference queues.

    In order to ensure that a reclaimable object remains so, the referent of a phantom reference may not be retrieved: The get method of a phantom reference always returns null.

    Since:
    1.2

constructor:PhantomReference(T, java.lang.ref.ReferenceQueue) [CHANGED]

  • PhantomReference

    public PhantomReferencepublic PhantomReference​(T referent,
                            ReferenceQueue<? super T> q)
    Creates a new phantom reference that refers to the given object and is registered with the given queue.

    It is possible to create a phantom reference with a null queue, but such a reference is completely useless: Its get method will always return null and, since it does not have a queue, it will never be enqueued.

    Parameters:
    referent - the object the new phantom reference will refer to
    q - the queue with which the reference is to be registered, or null if registration is not required
  • PhantomReference

    public PhantomReference(T referent,
                            ReferenceQueue<? super T> q)
    Creates a new phantom reference that refers to the given object and is registered with the given queue.

    It is possible to create a phantom reference with a null queue, but such a reference is completely useless: Its get method will always return null and, since it does not have a queue, it will never be enqueued.

    Parameters:
    referent - the object the new phantom reference will refer to
    q - the queue with which the reference is to be registered, or null if registration is not required
  • PhantomReference

    public PhantomReference​(T referent,
                            ReferenceQueue<? super T> q)
    Creates a new phantom reference that refers to the given object and is registered with the given queue.

    It is possible to create a phantom reference with a null queue, but such a reference is completely useless: Its get method will always return null and, since it does not have a queue, it will never be enqueued.

    Parameters:
    referent - the object the new phantom reference will refer to
    q - the queue with which the reference is to be registered, or null if registration is not required

method:get() [CHANGED]

  • get

    public T get get​()
    Returns this reference object's referent. Because the referent of a phantom reference is always inaccessible, this method always returns null.
    Overrides:
    get in class Reference<T>
    Returns:
    null
  • get

    public T get()
    Returns this reference object's referent. Because the referent of a phantom reference is always inaccessible, this method always returns null.
    Overrides:
    get in class Reference<T>
    Returns:
    null
  • get

    public T get​()
    Returns this reference object's referent. Because the referent of a phantom reference is always inaccessible, this method always returns null.
    Overrides:
    get in class Reference<T>
    Returns:
    null

© 2017 Oracle Corporation and/or its affiliates